Exemplary embodiments of this invention generally relate to emergency power supplies for aeronautical applications, and more particularly, to an improved ram air turbine for generating emergency power for an aircraft in flight.
Aircrafts include, as standard equipment, a back-up power source for use in times of power outage in the main power system. This standard equipment has been in the form of a ram air-driven turbine. The back-up equipment is stowed in a storage bay within the fuselage or wing of the aircraft. If/when needed, the back-up equipment can be deployed into the airstream where the passing air relative to the speed of the aircraft causes the turbine blades to rotate.
One example of such back-up equipment is a ram air turbine (RAT). A RAT may generate hydraulic power, electric power, or both. The turbine is coupled to suitable power generating equipment, such as a hydraulic pump for hydraulic power, or an electric generator for electric power, or both in the case of a hybrid RAT.
The RAT storage bay of the aircraft, as well as an access door to the RAT storage bay, are sized to store the ram air turbine and a deployment mechanism for the ram air turbine with only enough space to closely receive the equipment, thereby minimizing wasted space. In most cases, the structural configuration of the storage bay cannot be modified without compromising the structural integrity of the aircraft.
Due to the desire to reduce weight and maximize space, the overall size and particularly the length of newer ram air turbines has been reduced. Consequently, the bend radius of the conventional flexible sheath of the turbine release cable is too large to fit within the available space. In addition, for course pitch start up ram air turbines, the initial angle of the turbine blades applies a substantial load to the release cable thereby increasing the stress.